O21 Characterizing the impact of ageing/inflammageing on autophagy integrity in the skin
Kayumba Ng’andu, Jenny Pople, Ranjit Bhogal, Mike Philpott, Rosalind Hannen, Daniele BergamaschiAbstract
Introduction and aims
Epidermal and dermal homeostasis ensure the skin’s structural and functional integrity. Ageing deregulates this balance through extrinsic and intrinsic factors, promoting a low-grade chronic inflammatory profile (inflammaging), and an overall decline in the skin’s function. Autophagy – a process involving lysosomal degradation of autophagosome-packaged subcellular components – regulates skin homeostasis. However, the precise mechanisms by which ageing influences autophagic activity in the skin remains poorly understood. The present study aims to address this knowledge gap by elucidating the impact of ageing on autophagic function and exploring strategies to enhance autophagy to promote healthy skin ageing.
Methods
Proteomic approaches were employed to evaluate endogenous autophagy-related protein (ARP) expression across multiple skin compartments. Multiplex immunofluorescence analysis was performed on formalin-fixed paraffin-embedded skin tissues (n = 6) to assess spatial protein distribution. Western blot (WB) analysis was conducted on protein lysates derived from whole epidermal tissue (n = 9), and on lysates obtained from isolated human dermal fibroblasts (HDFs) (n = 11) to quantify ARP expression.
Results
Skin from younger donors exhibited a higher mean fluorescence intensity of lysosomal-associated membrane protein (LAMP)1 compared with skin from older donors. Further, younger donors showed widespread expression of ARPs throughout the epidermis, whereas older donors showed inconsistent patterns, with some samples displaying ARP expression restricted to suprabasal layers only. WB analysis of epidermal protein lysates corroborated these observations, revealing a relative decrease in LAMP1 and LAMP2 expression with age. Similarly, HDFs from older donors exhibited decreased LAMP1 levels, while conversely, an age-associated increase in the adaptor protein NDP52.
Conclusions
Older donor samples exhibited a decrease in lysosomal protein expression, alongside an increase of certain cargo receptors. These findings indicate that age-related autophagic flux decline may be linked to impaired lysosomal degradative function, underscoring the importance of targeting lysosomal pathways to restore homeostasis in skin ageing.